Curable phase change inks containing crystalline polyesters

ABSTRACT

This disclosure is generally directed to curable phase change inks, such as radiation-curable phase change inks, and their use in forming images, such as through inkjet printing. More specifically, this disclosure is directed to radiation-curable phase change inks, such as ultraviolet-light-curable phase change inks, that an ink vehicle and at least one crystalline polyester resin.

BACKGROUND

This disclosure is generally directed to curable phase change inks, suchas radiation-curable phase change inks, and their use in forming images,such as through inkjet printing. More specifically, this disclosure isdirected to radiation-curable phase change inks, such asultraviolet-light-curable phase change inks, that comprise a curablegellant and a crystalline polyester resin.

Inkjet printing systems are known in the art, and thus extensivedescription of such devices is not required herein. Phase change or “hotmelt” inks are desirable for ink jet printers because they remain in asolid phase at room temperature during shipping, long term storage, andthe like. In addition, the problems associated with nozzle clogging as aresult of ink evaporation with liquid ink jet inks are largelyeliminated, thereby improving the reliability of the ink jet printing.Further, in phase change ink jet printers wherein the ink droplets areapplied directly onto the final recording substrate (for example, paper,plastic, cardboard, and the like), the droplets solidify quickly uponcontact with the substrate, so that migration of ink along the printingmedium is substantially prevented and dot quality is improved.

While phase change inks enable more facile image printing and printingonto porous substrates, these inks may exhibit microbanding.Microbanding is an uneven distribution of ink in an image area in whichthe image should be smooth and uniform. Because the ink temperaturedrops after ejection, the ink freezes (or gels) quickly upon contactwith the substrate and an uneven distribution of ink on the imagesubstrate may occur. The human eye can sometimes observe the unevendistribution as bands or lines in the direction of the substrate travelpast the print head.

Microbanding may be addressed by leveling the ink on the image substrateby contact leveling. As used herein, the phrase “contact leveling” is aprocessing technique that employs a contact member, such as a roller,belt, press, wiper, to provide a sufficient amount of pressure to theink surface in an effort to normalize or smooth the ink distribution. Aheating element may be located near or within the contact member to heatit and consequently soften the ink for the leveling operation. Examplesof contact leveling techniques include those described in U.S. PatentApplication Pub. No. 2010/0103235, U.S. Patent Application Pub. No.2010/0101716 and U.S. Patent Application Pub. No. 2010/0101717, each ofwhich is incorporated by reference in their entirety. Additionalexamples of contact level techniques and apparatuses included thosedescribed in U.S. patent application Ser. No. 12/544,031, U.S. patentapplication Ser. No. 12/625,472 and U.S. patent application Ser. No.12/814,741, incorporated herein by reference in their entirety.

However, contact leveling the phase change ink is also subject toissues. For example, contact leveling the ink via contact member maycause the ink layer to split. A portion of the phase change ink may thusbe transferred to the contact member and affect the print quality oflater processed images. For example, a portion of the ink transferredfrom a contact member may later be deposited on subsequent mediacontacted by the contact member to leave a ghost of the previouslyleveled image. Further, ink build up on a contact member necessitateseither replacement of the contact member or removal of the ink from thecontact member on a periodic basis. Consequently, addressing themicrobanding defect of a phase change ink in an image without splittingthe ink or accumulating ink on a contact member would be useful. Whileuse of a release fluid in the contact leveling procedure may reduce inksplitting and transfer, elimination of the use of release fluids bydesign of inks that are less prone to splitting and offset may also beuseful.

SUMMARY

The curable phase change inks and process herein, addresses one or moreof the above issues. The curable phase change ink composition containingan ink vehicle and at least one crystalline polyester resin, and the useof such inks in methods for forming images, particularly their use ininkjet printing.

In embodiments, disclosed herein is an ink composition comprising an inkvehicle and at least one crystalline polyester resin.

In embodiments, disclosed herein is an ink printing device comprising: acurable phase change ink composition for printing onto a substrate, anink jetting device, a contact leveling member or roller, an optionalintermediate transfer member, and a curing device which cures the jettedcurable ink, wherein the ink composition comprises an ink vehicle and acrystalline polyester resin.

In embodiments, disclosed herein is a curable phase change inkcomposition, the ink composition comprising an ink vehicle and at leastone crystalline polyester resin, wherein the at least one crystallinepolyester resin has a weight average molecular weight (M_(w)) of fromabout 10,000 Dalton (Da) to about 60,000 Da, a number average molecularweight (M_(n)) of from about 5,000 Da to about 12,000 Da and apolydispersity of from about 2.0 to about 5.0, wherein the inkcomposition has elastic modulus (G′) of from about 3000 Pa to about 4000Pa, and a viscosity of about 10⁴ mPa·s to about 10^(6.5) mPa·s at agelling temperature of about 25° C. to about 35° C., and wherein the inkcomposition has a viscosity of from about 3 to about 15 mPa·s at ajetting temperature of from about 60° C. to about 100° C.

EMBODIMENTS

In this specification and the claims that follow, singular forms such as“a,” “an,” and “the” include plural forms unless the content clearlydictates otherwise. All ranges disclosed herein include, unlessspecifically indicated, all endpoints and intermediate values. Inaddition, reference may be made to a number of terms that shall bedefined as follows:

The term “functional group” refers, for example, to a group of atomsarranged in a way that determines the chemical properties of the groupand the molecule to which it is attached. Examples of functional groupsinclude halogen atoms, hydroxyl groups, carboxylic acid groups and thelike.

The term “long-chain” refers, for example, to hydrocarbon chains(CH₂)_(n) in which n represents the number of carbon atoms in the chainand wherein n is a number of from about 8 to about 60, such as fromabout 20 to about 45 or from about 30 to about 40. The term“short-chain” refers, for example, to hydrocarbon chains in which nrepresents the number of carbon atoms in the chain and wherein n is anumber of from 1 to about 7, such as from about 2 to about 5 or fromabout 3 to about 4.

The term “curable” describes, for example, a material that may be curedvia polymerization, including for example free radical routes, and/or inwhich polymerization is photoinitiated though use of aradiation-sensitive photoinitiator. The term “radiation-curable” refers,for example, to all forms of curing upon exposure to a radiation source,including light and heat sources and including in the presence orabsence of initiators. Exemplary radiation-curing techniques include,but are not limited to, curing using ultraviolet (UV) light, for examplehaving a wavelength of 200-400 nm or more rarely visible light,optionally in the presence of photoinitiators and/or sensitizers, curingusing electron-beam radiation, optionally in the absence ofphotoinitiators, curing using thermal curing, in the presence or absenceof high-temperature thermal initiators (and which may be largelyinactive at the jetting temperature), and appropriate combinationsthereof.

As used herein, the term “viscosity” refers to a complex viscosity,which is the typical measurement provided by a mechanical rheometer thatis capable of subjecting a sample to a steady shear strain or a smallamplitude sinusoidal deformation. In this type of instrument, the shearstrain is applied by the operator to the motor and the sampledeformation (torque) is measured by the transducer. Examples of suchinstruments are the Rheometrics Fluid Rheometer RFS3 or the ARESmechanical spectrometer, both made by Rheometrics, a division of TAInstruments. Alternatively, a controlled-stress instrument, where theshear stress is applied and the resultant strain is measured, may beused. Examples of such instruments are the majority of the currentrheometers, the main manufacturers being Anton Parr GmbH, BohlinInstruments, a division of Malvern Instruments, ATS Rheosystems and TAInstruments. Such a rheometer provides a periodic measurement ofviscosity at various plate rotation frequencies, ω, rather than thetransient measurement of, for instance, a capillary viscometer. Thereciprocating plate rheometer is able to measure both the in phase andout of phase fluid response to stress or displacement. The complexviscosity, η*, is defined as η*=η′−i η″; where η′=G″/ω, η″=G′/ω and i is√−1. Alternatively a viscometer that can measure only the transientmeasurement of, for instance, a capillary or shear viscosity, such asthose made by Brookfield Engineering Laboratories or Cannon InstrumentCompany can also be used.

“Optional” or “optionally” refer, for example, to instances in which thesubsequently described circumstance may or may not occur, and includeinstances in which the circumstance occurs and instances in which thecircumstance does not occur.

The terms “one or more” and “at least one” refer, for example, toinstances in which one of the subsequently described circumstancesoccurs, and to instances in which more than one of the subsequentlydescribed circumstances occurs.

Exemplary ink compositions provide superior print quality while meetingrequirements of piezoelectric ink jet printing processes. An exemplaryink composition includes an ink vehicle and a crystalline polyesterresin. In particular, exemplary ink compositions comprise an ink vehiclethat includes a curable monomer, a gellant, and a crystalline polyester.Additional exemplary ink compositions comprise an ink vehicle thatcomprises two or more chemically distinct curable gellants. Exemplarymethods of preparing such ink compositions and exemplary methods ofusing such ink compositions are also described.

In embodiments, the curable phase change ink is a gel at roomtemperature, or the gel can be realized as the ink composition coolsafter being jetted onto the substrate at the jetting temperature. Thecurable phase change ink may also be a solid at room temperature.

When the ink compositions described herein are in the gel state, theviscosity of the ink composition is at least about 1,000 mPa·s, such asat least about 10,000 mPa·s, or at least about 100,000 mPa·s. Theviscosity values in the gel state of exemplary ink compositions may bein the range of from about 10³ to about 10⁹ mPa·s, such as from about10^(4.5) to about 10^(6.5) mPa·s, at a gelling temperature. The gellingtemperature may be from about from about 20° C. to about 85° C., such asfrom about 25° C. to about 80° C., from about 25° C. to about 70° C.,from about 25° C. to about 65° C., or from about 25° C. to about 35° C.,such as about 30° C. Gel-phase viscosity of embodiments can vary withthe print process. For example, the highest viscosities may be suitablefor use in exemplary embodiments that employ intermediate transfer, orwhen jetting directly to porous paper in order to minimize the effectsof ink bleed and feathering. On the other hand, less porous substrates,such as plastic, may require lower viscosities that control dot gain andagglomeration of individual ink pixels. The gel viscosity can becontrolled by ink formulation and substrate temperature.

The curable phase change ink to have a viscosity of less than about 15mPa·s, such as less than about 12 mPa·s, for example from about 3 toabout 12 mPa·s, such as from about 5 to about 10 mPa·s, at thetemperature of jetting. The ink compositions may be jetted attemperatures of less than about 110° C., such as from about 40° C. toabout 100° C., from about 55° C. to about 100° C., from about 60° C. toabout 100° C., from about 70° C. to about 100° C. and from about 70° C.to about 90° C. Furthermore, the curable phase change ink may have anelastic modulus (G′) of from about 3000 Pa to about 4000 Pa, from about3100 Pa to about 3500 Pa and from about 3100 Pa to about 3300 Pa.

Crystalline Polyester Resin

In embodiments, the curable phase change ink includes a crystallinepolyester resin. As used herein, “crystalline” refers to a polyesterwith a three dimensional order. “Semicrystalline resins” as used hereinrefer to resins with a crystalline percentage of, for example, fromabout 10 to about 99%, and more specifically from about 10 to about 50%.Further, as used hereinafter “crystalline polyester resins” and“crystalline resins” encompass both crystalline resins andsemicrystalline resins, unless otherwise specified.

The crystalline polyester resins, which are available from a number ofsources, possess various melting points of, for example, from about 30°C. to about 120° C., such as from about 50° C. to about 90° C. Thecrystalline resin may have, for example, a number average molecularweight (M_(n)), as measured by gel permeation chromatography (GPC) of,for example, from about 5,000 to about 12,000 Daltons (Da), from about5,000 to about 11,000 Da, from about 6,000 to about 11,000 Da and fromabout 9,000 to about 11,000 Da. The weight average molecular weight(M_(w)) of the resin may be, for example, from about 10,000 to about60,000 Da, from about 15,000 to about 50,000 Da, from about 15,000 toabout 30,000 Da and from about 20,000 to about 22,000 Da, as determinedby GPC using polystyrene standards. The molecular weight distribution(M_(w)/M_(n)) or polydispersity of the crystalline resin is, forexample, from about 2 to about 5, from about 2 to about 4, from about 2to about 3, from about 2 to about 2.5 and from about 2 to about 2.2.

The polyester crystalline polyester resins can be prepared by apolycondensation process by reacting at least one organic diol and atleast one organic diacid in the presence of a polycondensation catalyst.Generally, a stoichiometric equimolar ratio of organic diol and organicdiacid is utilized, however, in some instances, wherein the boilingpoint of the organic diol is from about 180° C. to about 230° C., anexcess amount of diol can be utilized and removed during thepolycondensation process. The amount of catalyst utilized varies, andcan be selected in an amount, for example, of from about 0.01 to about 1mole percent of the resin. Additionally, in place of the organic diacid,an organic diester can also be selected, and where an alcohol byproductis generated.

Examples of organic diols include aliphatic diols with from about 2 toabout 36 carbon atoms, such as 2,2-dimethyl-1,3-propanediol,cyclohexanediol, triethylene glycol, dimer diol, benzenedimethanol,cyclohexanedimethanol, 2,2-dibutyl-1,3-propanediol,2,8-bis(hydroxymethyl) tricycle [5.2.1.0^(2,6)]decane,1,16-hexadecanediol and 2-phenyl-1,3-propanediol,tetrafluoro-1,4-butanediol, diethylene glycol, ethylene glycol,propylene glycol, 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol,1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, and the like; alkalisulfo-aliphatic diols such as sodio 2-sulfo-1,2-ethanediol, lithio2-sulfo-1,2-ethanediol, potassio 2-sulfo-1,2-ethanediol, sodio2-sulfo-1,3-propanediol, lithio 2-sulfo-1,3-propanediol, potassio2-sulfo-1,3-propanediol, mixture thereof, and the like. The aliphaticdiol is, for example, selected in an amount of from about 45 to about 50mole percent of the resin, and the alkali sulfo-aliphatic diol can beselected in an amount of from about 1 to about 10 mole percent of theresin.

Examples of organic diacids or diesters selected for the preparation ofthe crystalline polyester resins include oxalic acid, succinic acid,glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid,phthalic acid, isophthalic acid, terephthalic acid, dodecanedioic acid,fumaric acid, isophthalic acid, terephthalic acid, oxaloacetic acid,dimer diacid, malonic acid, tetrafluorosuccinic acid, methyl malonicacid, thiodiacetic acid, diglycolic acid, maleic acid, oxaloacetic acid,acetoxyacetic acid, cyclopropane-1,1-dicarboxylic acid, glutaconic acid,itaconic acid, 1,3-acetonedicarboxylic acid, ketoglutaric acid,dimethylmalonic acid, methylsuccinic acid, glutaric acid, muconic acid,cyclobutane-1,1-dicarboxylic acid, 2-oxoadipic acid,2,2-dimethylsuccinic acid, methylglutaric acid, 3,3′-thiodipropionicacid, 4-oxoheptanedioic acid, dimethylglutaric acid,cyclohexane-1,1-dicarboxylic acid, 5-oxoazelaic acid, phenylenediaceticacid, indan-2,2-dicarboxylic acid, tetradecanedioic acid,hexadecanedioic acid, napthalene-2,6-dicarboxylic acid,naphthalene-2,7-dicarboxylic acid, cyclohexane dicarboxylic acid,malonic acid and mesaconic acid, a diester or anhydride thereof; and analkali sulfo-organic diacid such as the sodio, lithio or potassium saltof dimethyl-5-sulfo-isophthalate,dialkyl-5-sulfo-isophthalate-4-sulfo-1,8-naphthalic anhydride,4-sulfo-phthalic acid, dimethyl-4-sulfo-phthalate,dialkyl-4-sulfo-phthalate, 4-sulfophenyl-3,5-dicarbomethoxybenzene,6-sulfo-2-naphthyl-3,5-dicarbometh-oxybenzene, sulfo-terephthalic acid,dimethyl-sulfo-terephthalate, 5-sulfo-isophthalic acid,dialkyl-sulfo-terephthalate, sulfoethanediol, 2-sulfopropanediol,2-sulfobutanediol, 3-sulfopentanediol, 2-sulfohexanediol,3-sulfo-2-methyl-pentanediol, 2-sulfo-3,3-dimethylpentanediol,sulfo-p-hydroxybenzoic acid, N,N-bis(2-hydroxyethyl)-2-amino ethanesulfonate, or mixtures thereof. The organic diacid is selected in anamount of, for example, from about 40 to about 50 mole percent of theresin, and the alkali sulfoaliphatic diacid can be selected in an amountof from about 1 to about 10 mole percent of the resin.

The molecular weight of the crystalline polyester can be controlledduring the synthesis by the inclusion of monofunctional acids such ascyclohexanecarboxylic acid, 3-(tert-Butoxy)propionic acid,2,2-Dimethylbutyric acid, hexanoic acid, stearic acid, octanoic acid ormonofunctional alcohols, such methyl cyclohexanol, hexanol, heptanol,octanol, 3,3-diethoxy-1-propanol, methylbenzyl alcohol,methoxyphenylethyl alcohol, dodecanol.

Illustrative examples of crystalline polyester resins may includepoly(ethylene-adipate), poly(propylene-adipate), poly(butylene-adipate),poly(pentylene-adipate), poly(hexylene-adipate), poly(octylene-adipate),poly(ethylene-succinate), poly(propylene-succinate),poly(butylene-succinate), poly(pentylene-succinate),poly(hexylene-succinate), poly(octylene-succinate),poly(ethylene-sebacate), polypropylene-sebacate),poly(butylene-sebacate), poly(pentylene-sebacate),poly(hexylene-sebacate), poly(octylene-sebacate),poly(nonylene-sebacate), poly(decylene-sebacate),poly(undecylene-sebacate), poly(dodecylene-sebacate),poly(ethylene-dodecanedioate), poly(propylene-dodecanedioate),poly(butylene-dodecanedioate), poly(pentylene-dodecanedioate),poly(hexylene-dodecanedioate), poly(octylene-dodecanedioate),poly(nonylene-dodecanedioate), poly(decylene-dodecandioate),poly(undecylene-dodecandioate), poly(dodecylene-dodecandioate),poly(ethylene-fumarate), poly(propylene-fumarate),poly(butylene-fumarate), poly(pentylene-fumarate),poly(hexylene-fumarate), poly(octylene-fumarate),poly(nonylene-fumarate), poly(decylene-fumarate),copoly(5-sulfoisophthaloyl)-copoly(ethylene-adipate),copoly(5-sulfoisophthaloyl)-copoly(propylene-adipate),copoly(5-sulfoisophthaloyl)-copoly(butylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate),copoly(5-sulfoisophthaloyl)-copoly(ethylene-succinate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-succinate),copoly(5-sulfo-isophthaloyl)-copoly(butylene-succinate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(hexylene-succinate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-succinate),copoly(5-sulfo-isophthaloyl)-copoly(ethylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(butylenes-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate) and combinationsthereof.

Suitable crystalline polyester resins also include those disclosed inU.S. Pat. No. 7,329,476 and U.S. Patent Application Pub. Nos.2006/0216626, 2008/0107990, 2008/0236446 and 2009/0047593, each of whichis hereby incorporated by reference in their entirety. In embodiments, asuitable crystalline resin may include a resin composed of ethyleneglycol and a mixture of dodecanedioic acid and fumaric acid co-monomerswith the following formula:

wherein b is from 5 to 2000 and d is from 5 to 2000.

If semicrystalline polyester resins are employed, the semicrystallineresin may include poly(3-methyl-1-butene), poly(hexamethylenecarbonate), poly(ethylene-p-carboxy phenoxy-butyrate),poly(ethylene-vinyl acetate), poly(docosyl acrylate), poly(dodecylacrylate), poly(octadecyl acrylate), poly(octadecyl methacrylate),poly(behenylpolyethoxyethyl methacrylate), poly(ethylene adipate),poly(decamethylene adipate), poly(decamethylene azelaate),poly(hexamethylene oxalate), poly(decamethylene oxalate), poly(ethyleneoxide), poly(propylene oxide), poly(butadiene oxide), poly(decamethyleneoxide), poly(decamethylene sulfide), poly(decamethylene disulfide),poly(ethylene sebacate), poly(decamethylene sebacate), poly(ethylenesuberate), poly(decamethylene succinate), poly(eicosamethylenemalonate), poly(ethylene-p-carboxy phenoxy-undecanoate), poly(ethylenedithionesophthalate), poly(methyl ethylene terephthalate),poly(ethylene-p-carboxy phenoxy-valerate),poly(hexamethylene-4,4′-oxydibenzoate), poly(10-hydroxy capric acid),poly(isophthalaldehyde), poly(octamethylene dodecanedioate),poly(dimethyl siloxane), poly(dipropyl siloxane), poly(tetramethylenephenylene diacetate), poly(tetramethylene trithiodicarboxylate),poly(trimethylene dodecane dioate), poly(m-xylene), poly(p-xylylenepimelamide), and combinations thereof.

The crystalline polyester may be present in the curable phase change inkcomposition in an amount of from about 0.1 weight percent to about 15weight percent, from about 1 weight percent to about 10 weight percent,from about 1 weight percent to about 7.5 weight percent, from about 1weight percent to about 5 weight percent from about 1.5 weight percentto about 4 weight percent and from about 2 weight percent to about 3.5weight percent of the curable phase change ink.

Upon jetting or printing the curable phase change at a jettingtemperature less than 110° C., the amount of crystalline polyester resinin the curable phase change ink composition is from 1 to about 5 weightpercent. However, if the curable phase change ink composition is jettedat a temperature greater than 110° C., an additional amount ofcrystalline polyester resin may be added.

Curable Monomers

In embodiments, the curable phase change ink includes an ink vehiclecomprised of at least a gellant, at least a curable wax, an optionalphotoinitiator, an optional colorant, and at least a curable monomer. Inembodiments, if more than one curable liquid monomer is present in thecurable phase change ink, the curable liquid monomers are referred to“co-monomers”. The co-monomers may be chosen from any suitable curablemonomers.

Ink compositions of embodiments may comprise a first co-monomer, due tothe solubility and gelling properties of gellant materials, such as,epoxy-polyamide composite gellants, which are useful for producing inkcompositions including an ink vehicle having a thermally-driven andreversible gel phase, where the ink vehicle is comprised of curableliquid monomers, such as UV-curable liquid monomers. The gel phase ofsuch ink compositions allows an ink droplet to be pinned to a receivingsubstrate.

Examples of the at least one curable monomer of the composition includepropoxylated neopentyl glycol diacrylate (such as SR-9003 fromSartomer), diethylene glycol diacrylate, triethylene glycol diacrylate,butanediol diacrylate, hexanediol diacrylate, dipropyleneglycoldiacrylate, tripropylene glycol diacrylate, alkoxylated neopentyl glycoldiacrylate, isodecyl acrylate, tridecyl acrylate, isobornyl acrylate,isobornyl(meth)acrylate, propoxylated trimethylolpropane triacrylate,ethoxylated trimethylolpropane triacrylate, di-trimethylolpropanetetraacrylate, dipentaerythritol pentaacrylate, ethoxylatedpentaerythritol tetraacrylate, propoxylated glycerol triacrylate,isobornyl methacrylate, lauryl acrylate, lauryl methacrylate, neopentylglycol propoxylate methylether monoacrylate, isodecylmethacrylate,caprolactone acrylate, 2-phenoxyethyl acrylate, isooctylacrylate,isooctylmethacrylate, tricyclodecane dimethanol diacrylate, dioxaneglycol diacrylate, mixtures thereof and the like. As relativelynon-polar monomers, mention may be made of isodecyl(meth)acrylate,caprolactone acrylate, 2-phenoxyethyl acrylate, isooctyl(meth)acrylate,and butyl acrylate. In addition, multifunctional acrylatemonomers/oligomers may be used not only as reactive diluents, but alsoas materials that can increase the cross-link density of the curedimage, thereby enhancing the toughness of the cured images.

The term “curable monomer” is also intended to encompass curableoligomers, which may also be used in the composition. Examples ofsuitable curable oligomers that may be used in the compositions have alow viscosity, for example, from about 50 cPs to about 10,000 cPs, suchas from about 75 cPs to about 7,500 cPs or from about 100 cPs to about5,000 cPs. Examples of such oligomers may include CN549, CN131, CN131B,CN2285, CN 3100, CN3105, CN132, CN133, CN 132, available from SartomerCompany, Inc., Exeter, Pa., Ebecryl 140, Ebecryl 1140, Ebecryl 40,Ebecryl 3200, Ebecryl 3201, Ebecryl 3212, available from CytecIndustries Inc, Smyrna Ga., PHOTOMER 3660, PHOTOMER 5006F, PHOTOMER5429, PHOTOMER 5429F, available from Cognis Corporation, Cincinnati,Ohio, LAROMER PO 33F, LAROMER PO 43F, LAROMER PO 94F, LAROMER UO 35D,LAROMER PA 9039V, LAROMER PO 9026V, LAROMER 8996, LAROMER 8765, LAROMER8986, available from BASF Corporation, Florham Park, N.J., and the like.As multifunctional acrylates and methacrylates, mention may also be madeof pentaerythritol tetra(meth)acrylate, 1,2 ethylene glycoldi(meth)acrylate, 1,6 hexanediol di(meth)acrylate, 1,12-dodecanoldi(meth)acrylate, tris(2-hydroxy ethyl) isocyanurate triacrylate,propoxylated neopentyl glycol diacrylate, hexanediol diacrylate,tripropylene glycol diacrylate, dipropylene glycol diacrylate,amine-modified polyether acrylates (available as PO 83 F, LR 8869,and/or LR 8889 (all available from BASF Corporation)),trimethylolpropane triacrylate, glycerol propoxylate triacrylate,dipentaerythritol penta-/hexa-acrylate, ethoxylated pentaerythritoltetraacrylate (available from Sartomer Co. Inc. as SR399LV and SR 494),and the like.

Additional examples of the curable monomers include acrylated esters,acrylated polyesters, acrylated ethers, acrylated polyethers, acrylatedepoxies, urethane acrylates, and pentaerythritol tetraacrylate. Specificexamples of suitable acrylated oligomers include, acrylated polyesteroligomers, such as CN2262 (Sartomer Co.), EB 812 (Cytec SurfaceSpecialties), EB 810 (Cytec Surface Specialties), CN2200 (Sartomer Co.),CN2300 (Sartomer Co.), and the like; acrylated urethane oligomers, suchas EB270 (UCB Chemicals), EB 5129 (Cytec Surface Specialties), CN2920(Sartomer Co.), CN3211 (Sartomer Co.), and the like; and acrylated epoxyoligomers, such as EB 600 (Cytec Surface Specialties), EB 3411 (CytecSurface Specialties), CN2204 (Sartomer Co.), CN110 (Sartomer Co.), andthe like.

In embodiments, the curable monomer may be chosen from short-chain alkylglycol diacrylates or ether diacrylates or from acrylates havingshort-chain alkyl ester substituents, such as caprolactone acrylate, andthe commercially available products CD536, CD 2777, CD585 and CD586(available from Sartomer Co. Inc.).

In addition, the curable monomer or oligomer may variously function as aviscosity reducer, as a binder when the composition is cured, as anadhesion promoter, as a reactive diluent and as a crosslinking agentthat can increase the crosslink density of the cured image, therebyenhancing the toughness of the cured images. Suitable monomers may havea low molecular weight, low viscosity, and low surface tension andcomprise functional groups that undergo polymerization upon exposure toradiation such as UV light.

The curable phase change ink compositions of embodiments may include oneor more co-monomers in an amount ranging from about 5% to about 80% byweight, such as from about 20% to about 70% by weight, or from about 30%to about 60% by weight, relative to the total weight of the ink vehicle.

Curable Gellants

The curable phase change ink composition may include at least onegellant.

The organic gellants function to dramatically increase the viscosity ofthe ink vehicle and ink composition within a desired temperature range.In particular, the gellant forms a semi-solid gel in the ink vehicle attemperatures below the specific temperature at which the ink compositionis jetted. The semi-solid gel phase is a physical gel that exists as adynamic equilibrium comprised of one or more solid gellant molecules anda liquid solvent. The semi-solid gel phase is a dynamic networkedassembly of molecular components held together by non-covalent bondinginteractions such as hydrogen bonding, Van der Waals interactions,aromatic non-bonding interactions, ionic or coordination bonding, Londondispersion forces, and the like, which upon stimulation by physicalforces such as temperature or mechanical agitation or chemical forcessuch as pH or ionic strength, can reversibly transition from liquid tosemi-solid state at the macroscopic level. The ink compositions exhibita thermally reversible transition between the semi-solid gel state andthe liquid state when the temperature is varied above or below thegel-phase transition. This reversible cycle of transitioning betweensemi-solid gel phase and liquid phase can be repeated many times in theink formulation. Mixtures of one or more gellants may be used to effectthe phase change transition.

The phase change nature of the gellant can thus be used to cause a rapidviscosity increase in the jetted ink composition upon the substratefollowing jetting of the ink to the substrate. In particular, jetted inkdroplets would be pinned into position on a receiving substrate, such asan image-receiving medium (for instance, paper), that is at atemperature cooler than the ink jetting temperature of the inkcomposition through the action of a phase change transition in which theink composition undergoes a significant viscosity change from a liquidstate to a gel state (or semi-solid state).

In embodiments, the temperature at which the ink composition forms thegel state is any temperature below the jetting temperature of the inkcomposition, for example any temperature that is about 10° C. or morebelow the jetting temperature of the ink composition. There is a rapidand large increase in ink viscosity upon cooling from the jettingtemperature at which the ink composition is in a liquid state, to thegel transition temperature, at which the ink composition converts to thegel state.

A suitable gellant for the ink composition would gel themonomers/oligomers in the ink vehicle quickly and reversibly, anddemonstrate a narrow phase change transition, for example within atemperature range of about 20° C. to about 85° C. The gel state ofexemplary ink compositions should exhibit a minimum of 10^(2.5) mPa·s,such as 10³ mPa·s, increase in viscosity at substrate temperatures, forinstance, from about 30° C. to about 70° C., compared to the viscosityat the jetting temperature. In particular embodiments, thegellant-containing ink compositions rapidly increase in viscosity within5° C. to 10° C. below the jetting temperature and ultimately reach aviscosity above 10⁴ times the jetting viscosity, for example about 10⁵times the jetting viscosity.

Gellants suitable for use in the ink compositions include a curablegellant comprised of a curable amide, a curable polyamide-epoxy acrylatecomponent and a polyamide component, a curable composite gellantcomprised of a curable epoxy resin and a polyamide resin, mixturesthereof and the like, as disclosed in U.S. patent application Ser. No.12/474,946, which is hereby incorporated herein by reference in itsentirety. Inclusion of the gellant in the composition permits thecomposition to be applied over a substrate, such as on one or moreportions of the substrate and/or on one or more portions of an imagepreviously formed on the substrate, without excessive penetration intothe substrate because the viscosity of the composition is quicklyincreased as the composition cools following application. Excessivepenetration of a liquid into a porous substrate, such as paper, can leadto an undesirable decrease in the substrate opacity. The curable gellantmay also participate in the curing of monomer(s) of the composition.

The gellants suitable for use in the composition may be amphiphilic innature in order to improve wetting when the composition is utilized overa substrate having silicone or other oil thereon. Amphiphilic refers tomolecules that have both polar and non-polar parts of the molecule. Forexample, the gellants may have long non-polar hydrocarbon chains andpolar amide linkages.

Amide gellants suitable for use include those described in U.S. PatentApplication Publication No. 2008/0122914 and U.S. Pat. Nos. 7,276,614and 7,279,587, the entire disclosures of which are incorporated hereinby reference.

As described in U.S. Pat. No. 7,279,587, the amide gellant may be acompound of the formula

wherein:

-   R₁ is:-   (i) an alkylene group (wherein an alkylene group is a divalent    aliphatic group or alkyl group, including linear and branched,    saturated and unsaturated, cyclic and acyclic, and substituted and    unsubstituted alkylene groups, and wherein heteroatoms, such as    oxygen, nitrogen, sulfur, silicon, phosphorus, boron, and the like    either may or may not be present in the alkylene group) having from    about 1 carbon atom to about 12 carbon atoms, such as from about 1    carbon atom to about 8 carbon atoms or from about 1 carbon atom to    about 5 carbon atoms,-   (ii) an arylene group (wherein an arylene group is a divalent    aromatic group or aryl group, including substituted and    unsubstituted arylene groups, and wherein heteroatoms, such as    oxygen, nitrogen, sulfur, silicon, phosphorus, boron, and the like    either may or may not be present in the arylene group) having from    about 1 carbon atom to about 15 carbon atoms, such as from about 3    carbon atoms to about 10 carbon atoms or from about 5 carbon atoms    to about 8 carbon atoms,-   (iii) an arylalkylene group (wherein an arylalkylene group is a    divalent arylalkyl group, including substituted and unsubstituted    arylalkylene groups, wherein the alkyl portion of the arylalkylene    group can be linear or branched, saturated or unsaturated, and    cyclic or acyclic, and wherein heteroatoms, such as oxygen,    nitrogen, sulfur, silicon, phosphorus, boron, and the like either    may or may not be present in either the aryl or the alkyl portion of    the arylalkylene group) having from about 6 carbon atoms to about 32    carbon atoms, such as from about 6 carbon atoms to about 22 carbon    atoms or from about 6 carbon atoms to about 12 carbon atoms, or-   (iv) an alkylarylene group (wherein an alkylarylene group is a    divalent alkylaryl group, including substituted and unsubstituted    alkylarylene groups, wherein the alkyl portion of the alkylarylene    group can be linear or branched, saturated or unsaturated, and    cyclic or acyclic, and wherein heteroatoms, such as oxygen,    nitrogen, sulfur, silicon, phosphorus, boron, and the like either    may or may not be present in either the aryl or the alkyl portion of    the alkylarylene group) having from about 5 carbon atoms to about 32    carbon atoms, such as from about 6 carbon atoms to about 22 carbon    atoms or from about 7 carbon atoms to about 15 carbon atoms,-   wherein the substituents on the substituted alkylene, arylene,    arylalkylene, and alkylarylene groups can be halogen atoms, cyano    groups, pyridine groups, pyridinium groups, ether groups, aldehyde    groups, ketone groups, ester groups, amide groups, carbonyl groups,    thiocarbonyl groups, sulfide groups, nitro groups, nitroso groups,    acyl groups, azo groups, urethane groups, urea groups, mixtures    thereof, and the like, wherein two or more substituents can be    joined together to form a ring;

R₂ and R₂′ each, independently of the other, are:

-   (i) alkylene groups having from about 1 carbon atom to about 54    carbon atoms, such as from about 1 carbon atom to about 48 carbon    atoms or from about 1 carbon atom to about 36 carbon atoms,-   (ii) arylene groups having from about 5 carbon atoms to about 15    carbon atoms, such as from about 5 carbon atoms to about 13 carbon    atoms or from about 5 carbon atoms to about 10 carbon atoms,-   (iii) arylalkylene groups having from about 6 carbon atoms to about    32 carbon atoms, such as from about 7 carbon atoms to about 33    carbon atoms or from about 8 carbon atoms to about 15 carbon atoms,    or-   (iv) alkylarylene groups having from about 6 carbon atoms to about    32 carbon atoms, such as from about 6 carbon atoms to about 22    carbon atoms or from about 7 carbon atoms to about 15 carbon atoms,

wherein the substituents on the substituted alkylene, arylene,arylalkylene, and alkylarylene groups may be halogen atoms, cyanogroups, ether groups, aldehyde groups, ketone groups, ester groups,amide groups, carbonyl groups, thiocarbonyl groups, phosphine groups,phosphonium groups, phosphate groups, nitrile groups, mercapto groups,nitro groups, nitroso groups, acyl groups, acid anhydride groups, azidegroups, azo groups, cyanato groups, urethane groups, urea groups,mixtures thereof, and the like, and wherein two or more substituents maybe joined together to form a ring;

R₃ and R₃′ each, independently of the other, are either:

(a) photoinitiating groups, such as groups derived from1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methylpropan-1-one, of theformula

groups derived from 1-hydroxycyclohexylphenylketone, of the formula

groups derived from 2-hydroxy-2-methyl-1-phenylpropan-1-one, of theformula

groups derived from N,N-dimethylethanolamine orN,N-dimethylethylenediamine, of the formula

or the like, or:

(b) a group which is:

-   (i) an alkyl group (including linear and branched, saturated and    unsaturated, cyclic and acyclic, and substituted and unsubstituted    alkyl groups, and wherein heteroatoms, such as oxygen, nitrogen,    sulfur, silicon, phosphorus, boron, and the like either may or may    not be present in the alkyl group) having from about 2 carbon atoms    to about 100 carbon atoms, such as from about 3 carbon atoms to    about 60 carbon atoms or from about 4 carbon atoms to about 30    carbon atoms,-   (ii) an aryl group (including substituted and unsubstituted aryl    groups, and wherein heteroatoms, such as oxygen, nitrogen, sulfur,    silicon, phosphorus, boron, and the like either may or may not be    present in the aryl group) having from about 5 carbon atoms to about    100 carbon atoms, such as from about 5 carbon atoms to about 60    carbon atoms or from about 6 carbon atoms to about 30 carbon atoms,    such as phenyl or the like,-   (iii) an arylalkyl group (including substituted and unsubstituted    arylalkyl groups, wherein the alkyl portion of the arylalkyl group    can be linear or branched, saturated or unsaturated, and cyclic or    acyclic, and wherein heteroatoms, such as oxygen, nitrogen, sulfur,    silicon, phosphorus, boron, and the like either may or may not be    present in either the aryl or the alkyl portion of the arylalkyl    group) having from about 5 carbon atoms to about 100 carbon atoms,    such as from about 5 carbon atoms to about 60 carbon atoms or from    about 6 carbon atoms to about 30 carbon atoms, such as benzyl or the    like, or-   (iv) an alkylaryl group (including substituted and unsubstituted    alkylaryl groups, wherein the alkyl portion of the alkylaryl group    can be linear or branched, saturated or unsaturated, and cyclic or    acyclic, and wherein heteroatoms, such as oxygen, nitrogen, sulfur,    silicon, phosphorus, boron, and the like either may or may not be    present in either the aryl or the alkyl portion of the alkylaryl    group) having from about 5 carbon atoms to about 100 carbon atoms,    such as from about 5 carbon atoms to about 60 carbon atoms or from    about 6 carbon atoms to about 30 carbon atoms, such as tolyl or the    like,

wherein the substituents on the substituted alkyl, arylalkyl, andalkylaryl groups may be halogen atoms, ether groups, aldehyde groups,ketone groups, ester groups, amide groups, carbonyl groups, thiocarbonylgroups, sulfide groups, phosphine groups, phosphonium groups, phosphategroups, nitrile groups, mercapto groups, nitro groups, nitroso groups,acyl groups, acid anhydride groups, azide groups, azo groups, cyanatogroups, isocyanato groups, thiocyanato groups, isothiocyanato groups,carboxylate groups, carboxylic acid groups, urethane groups, ureagroups, mixtures thereof, and the like, and wherein two or moresubstituents may be joined together to form a ring;

and X and X′ each, independently of the other, is an oxygen atom or agroup of the formula —NR₄—, wherein R₄ is:

(i) a hydrogen atom;

(ii) an alkyl group, including linear and branched, saturated andunsaturated, cyclic and acyclic, and substituted and unsubstituted alkylgroups, and wherein heteroatoms either may or may not be present in thealkyl group, having from about 5 carbon atoms to about 100 carbon atoms,such as from about 5 carbon atoms to about 60 carbon atoms or from about6 carbon atoms to about 30 carbon atoms,

(iii) an aryl group, including substituted and unsubstituted arylgroups, and wherein heteroatoms either may or may not be present in thearyl group, having from about 5 carbon atoms to about 100 carbon atoms,such as from about 5 carbon atoms to about 60 carbon atoms or from about6 carbon atoms to about 30 carbon atoms,

(iv) an arylalkyl group, including substituted and unsubstitutedarylalkyl groups, wherein the alkyl portion of the arylalkyl group maybe linear or branched, saturated or unsaturated, and cyclic or acyclic,and wherein heteroatoms either may or may not be present in either thearyl or the alkyl portion of the arylalkyl group, having from about 5carbon atoms to about 100 carbon atoms, such as from about 5 carbonatoms to about 60 carbon atoms or from about 6 carbon atoms to about 30carbon atoms, or

(v) an alkylaryl group, including substituted and unsubstitutedalkylaryl groups, wherein the alkyl portion of the alkylaryl group canbe linear or branched, saturated or unsaturated, and cyclic or acyclic,and wherein heteroatoms either may or may not be present in either thearyl or the alkyl portion of the alkylaryl group, having from about 5carbon atoms to about 100 carbon atoms, such as from about 5 carbonatoms to about 60 carbon atoms or from about 6 carbon atoms to about 30carbon atoms,

wherein the substituents on the substituted alkyl, aryl, arylalkyl, andalkylaryl groups may be halogen atoms, ether groups, aldehyde groups,ketone groups, ester groups, amide groups, carbonyl groups, thiocarbonylgroups, sulfate groups, sulfonate groups, sulfonic acid groups, sulfidegroups, sulfoxide groups, phosphine groups, phosphonium groups,phosphate groups, nitrile groups, mercapto groups, nitro groups, nitrosogroups, sulfone groups, acyl groups, acid anhydride groups, azidegroups, azo groups, cyanato groups, isocyanato groups, thiocyanatogroups, isothiocyanato groups, carboxylate groups, carboxylic acidgroups, urethane groups, urea groups, mixtures thereof, and the like,and wherein two or more substituents may be joined together to form aring.

Specific suitable substituents and gellants of the above are further setforth in U.S. Pat. Nos. 7,279,587 and 7,276,614, incorporated herein byreference in their entireties, and thus are not further detailed herein.

In embodiments, the gellant may comprise a mixture comprising:

wherein —C₃₄H_(56+a)— represents a branched alkylene group which mayinclude unsaturations and cyclic groups, wherein the variable “a” is aninteger from 0-12.

In embodiments, the gellant may be a composite gellant, for examplecomprised of a curable epoxy resin and a polyamide resin. Suitablecomposite gellants are described in commonly assigned U.S. PatentApplication Publication No. 2007/0120921, the entire disclosure of whichis incorporated herein by reference.

The epoxy resin component in the composite gellant can be any suitableepoxy group-containing material. In embodiments, the epoxy groupcontaining component includes the diglycidyl ethers of eitherpolyphenol-based epoxy resin or a polyol-based epoxy resin, or mixturesthereof. That is, in embodiments, the epoxy resin has two epoxyfunctional groups that are located at the terminal ends of the molecule.The polyphenol-based epoxy resin in embodiments is a bisphenolA-co-epichlorohydrin resin with not more than two glycidyl etherterminal groups. The polyol-based epoxy resin can be a dipropyleneglycol-co-epichlorohydrin resin with not more than two glycidyl etherterminal groups. Suitable epoxy resins have a weight average molecularweight in the range of from about 200 to about 800, such as from about300 to about 700. Commercially available sources of the epoxy resinsare, for example, the bisphenol-A based epoxy resins from Dow ChemicalCorp. such as DER 383, or the dipropyleneglycol-based resins from DowChemical Corp. such as DER 736. Other sources of epoxy-based materialsoriginating from natural sources may be used, such as epoxidizedtriglyceride fatty esters of vegetable or animal origins, for exampleepoxidized linseed oil, rapeseed oil and the like, or mixtures thereof.Epoxy compounds derived from vegetable oils such as the VIKOFLEX line ofproducts from Arkema Inc., Philadelphia Pa. may also be used. The epoxyresin component is thus functionalized with acrylate or (meth)acrylate,vinyl ether, allyl ether and the like, by chemical reaction withunsaturated carboxylic acids or other unsaturated reagents. For example,the terminal epoxide groups of the resin become ring-opened in thischemical reaction, and are converted to (meth)acrylate esters byesterification reaction with (meth)acrylic acid.

As the polyamide component of the epoxy-polyamide composite gellant, anysuitable polyamide material may be used. In embodiments, the polyamideis comprised of a polyamide resin derived from a polymerized fatty acidsuch as those obtained from natural sources (for example, palm oil,rapeseed oil, castor oil, and the like, including mixtures thereof) orthe commonly known hydrocarbon “dimer acid,” prepared from dimerizedC-18 unsaturated acid feedstocks such as oleic acid, linoleic acid andthe like, and a polyamine, such as a diamine (for example,alkylenediamines such as ethylenediamine, DYTEK® series diamines,poly(alkyleneoxy)diamines, and the like), or also copolymers ofpolyamides such as polyester-polyamides and polyether-polyamides. One ormore polyamide resins may be used in the formation of the gellant.Commercially available sources of the polyamide resin include, forexample, the VERSAMID series of polyamides available from CognisCorporation (formerly Henkel Corp.), in particular VERSAMID 335,VERSAMID 338, VERSAMID 795 and VERSAMID 963, all of which have lowmolecular weights and low amine numbers. The SYLVAGEL® polyamide resinsfrom Arizona Chemical Company, and variants thereof includingpolyether-polyamide resins may be employed. The composition of theSYLVAGEL® resins obtained from Arizona Chemical Company are described aspolyalkyleneoxydiamine polyamides with the general formula,

wherein R₁ is an alkyl group having at least seventeen carbons, R₂includes a polyalkyleneoxide, R₃ includes a C-6 carbocyclic group, and nis an integer of at least 1, such as from 1 to about 100, from about 1to about 50 and from about 5 to about 25.

The gellant may also comprise a curable polyamide-epoxy acrylatecomponent and a polyamide component, such as disclosed, for example, incommonly assigned U.S. Patent Application Publication No. 2007/0120924,the entire disclosure of which is incorporated herein by reference. Thecurable polyamide-epoxy acrylate is curable by virtue of including atleast one functional group therein. As an example, the polyamide-epoxyacrylate is difunctional. The functional group(s), such as the acrylategroup(s), are curable via free-radical initiation and enable chemicalbonding of the gellant to the cured ink vehicle. A commerciallyavailable polyamide-epoxy acrylate is PHOTOMER RM370 from Cognis. Thecurable polyamide-epoxy acrylate may also be selected from within thestructures described above for the curable composite gellant comprisedof a curable epoxy resin and a polyamide resin.

The ink composition may include the gellant in any suitable amount, suchas about 1% to about 50% by weight of the composition. In embodiments,the gellant may be present in an amount of about 2% to about 20% byweight of the composition, such as about 3% to about 10% by weight ofthe composition.

The ink composition may include at least one curable wax. The wax may bea solid at room temperature (25° C.). Inclusion of the wax may promotean increase in viscosity of the ink composition as the composition coolsfrom the application temperature. Thus, the wax may also assist thegellant in avoiding bleeding of the composition through the substrate.

The curable wax may be any wax component that is miscible with the othercomponents and that will polymerize with the curable monomer to form apolymer. The term wax includes, for example, any of the various natural,modified natural, and synthetic materials commonly referred to as waxes.

Suitable examples of curable waxes include waxes that include or arefunctionalized with curable groups. The curable groups may include, forexample, an acrylate, methacrylate, alkene, allylic ether, epoxide,oxetane, and the like. These waxes can be synthesized by the reaction ofa wax, such as a polyethylene wax equipped with a carboxylic acid orhydroxyl transformable functional group. The curable waxes describedherein may be cured with the above curable monomer(s).

Suitable examples of hydroxyl-terminated polyethylene waxes that may befunctionalized with a curable group include, but are not limited to,mixtures of carbon chains with the structure CH₃—(CH₂)_(n)—CH₂OH, wherethere is a mixture of chain lengths, n, where the average chain lengthcan be in the range of about 16 to about 50, and linear low molecularweight polyethylene, of similar average chain length. Suitable examplesof such waxes include, but are not limited to, the UNILIN series ofmaterials such as UNILIN 350, UNILIN 425, UNILIN 550 and UNILIN 700 withM_(n) approximately equal to 375, 460, 550 and 700 g/mol, respectively.All of these waxes are commercially available from Baker-Petrolite.Guerbet alcohols, characterized as 2,2-dialkyl-1-ethanols, are alsosuitable compounds. Exemplary Guerbet alcohols include those containingabout 16 to about 36 carbons, many of which are commercially availablefrom Jarchem Industries Inc., Newark, N.J. PRIPOL® 2033 (C-36 dimer diolmixture including isomers of the formula

as well as other branched isomers that may include unsaturations andcyclic groups, available from Uniqema, New Castle, Del.; furtherinformation on C₃₆ dimer diols of this type is disclosed in, forexample, “Dimer Acids,” Kirk-Othmer Encyclopedia of Chemical Technology,Vol. 8, 4^(th) Ed. (1992), pp. 223 to 237, the disclosure of which istotally incorporated herein by reference, may also be used. Thesealcohols can be reacted with carboxylic acids equipped with UV curablemoieties to form reactive esters. Examples of these acids includeacrylic and methacrylic acids, available from Sigma-Aldrich Co.

Suitable examples of carboxylic acid-terminated polyethylene waxes thatmay be functionalized with a curable group include mixtures of carbonchains with the structure CH₃—(CH₂)_(n)—COOH, where there is a mixtureof chain lengths, n, where the average chain length is about 16 to about50, and linear low molecular weight polyethylene, of similar averagechain length. Suitable examples of such waxes include, but are notlimited to, UNICID® 350, UNICID® 425, UNICID® 550 and UNICID® 700 withM_(n) equal to approximately 390, 475, 565 and 720 g/mol, respectively.Other suitable waxes have a structure CH₃—(CH₂)_(n)—COOH, such ashexadecanoic or palmitic acid with n=14, heptadecanoic or margaric ordaturic acid with n=15, octadecanoic or stearic acid with n=16,eicosanoic or arachidic acid with n=18, docosanoic or behenic acid withn=20, tetracosanoic or lignoceric acid with n=22, hexacosanoic orcerotic acid with n=24, heptacosanoic or carboceric acid with n=25,octacosanoic or montanic acid with n=26, triacontanoic or melissic acidwith n=28, dotriacontanoic or lacceroic acid with n=30, tritriacontanoicor ceromelissic or psyllic acid, with n=31, tetratriacontanoic or geddicacid with n=32, pentatriacontanoic or ceroplastic acid with n=33.Guerbet acids, characterized as 2,2-dialkyl ethanoic acids, are alsosuitable compounds. Exemplary Guerbet acids include those containing 16to 36 carbons, many of which are commercially available from JarchemIndustries Inc., Newark, N.J. PRIPOL® 1009 (C-36 dimer acid mixtureincluding isomers of the formula

as well as other branched isomers that may include unsaturations andcyclic groups, available from Uniqema, New Castle, Del.; furtherinformation on C₃₆ dimer acids of this type is disclosed in, forexample, “Dimer Acids,” Kirk-Othmer Encyclopedia of Chemical Technology,Vol. 8, 4^(th) Ed. (1992), pp. 223 to 237, the disclosure of which istotally incorporated herein by reference, can also be used. Thesecarboxylic acids can be reacted with alcohols equipped with UV curablemoieties to form reactive esters. Examples of these alcohols include,but are not limited to, 2-allyloxyethanol from Sigma-Aldrich Co.;

SR495B from Sartomer Company, Inc.;

CD572 (R═H, n=10) and SR604 (R=Me, n=4) from Sartomer Company, Inc.

The curable wax can be included in the composition in an amount of from,for example, about 0.1% to about 30% by weight of the composition, suchas from about 0.5% to about 20% or from about 0.5% to 15% by weight ofthe composition.

Optional Additives

The ink vehicles of embodiments may be mixtures of curable componentsand, optionally, additional materials including additional curablemonomers, colorants, initiating agents, antioxidants, as well as anyconventional optional additives. Such conventional additives mayinclude, for example, defoamers, slip and leveling agents, surfactants,pigment dispersants and the like. The inks may also include additionalmonomeric or polymeric materials as desired.

Colorants

The ink compositions may optionally contain a colorant. Any desired oreffective colorant can be employed in the ink compositions, includingdyes, pigments, mixtures thereof, and the like, provided that thecolorant can be dissolved or dispersed in the ink vehicle. Pigments,which are typically cheaper and more robust than dyes, may be includedin particular embodiments. The color of many dyes can be altered by thepolymerization process occurring during the curing stage, presumablyfrom attack of their molecular structure by the free radicals. Thecompositions can be used in combination with conventional ink-colorantmaterials, such as Color Index (C.I.) Solvent Dyes, Disperse Dyes,modified Acid and Direct Dyes, Basic Dyes, Sulphur Dyes, Vat Dyes, andthe like.

Examples of suitable dyes include Neozapon Red 492 (BASF); Orasol Red G(Ciba); Direct Brilliant Pink B (Oriental Giant Dyes); Direct Red 3BL(Classic Dyestuffs); Supranol Brilliant Red 3BW (Bayer AG); Lemon Yellow6G (United Chemie); Light Fast Yellow 3G (Shaanxi); Aizen Spilon YellowC-GNH (Hodogaya Chemical); Bernachrome Yellow GD Sub (ClassicDyestuffs); Cartasol Brilliant Yellow 4GF (Clariant); Cibanon Yellow 2GN(Ciba); Orasol Black CN (Ciba); Savinyl Black RLSN (Clariant); PyrazolBlack BG (Clariant); Morfast Black 101 (Rohm & Haas); Diaazol Black RN(ICI); Orasol Blue GN (Ciba); Savinyl Blue GLS (Clariant); Luxol FastBlue MBSN (Pylam Products); Sevron Blue 5GMF (Classic Dyestuffs);Basacid Blue 750 (BASF), Neozapon Black X51 (BASF), Classic SolventBlack 7 (Classic Dyestuffs), Sudan Blue 670 (C.I. 61554) (BASF), SudanYellow 146 (C.I. 12700) (BASF), Sudan Red 462 (C.I. 26050) (BASF), C.I.Disperse Yellow 238, Neptune Red Base NB543 (BASF, C.I. Solvent Red 49),Neopen Blue FF-4012 from BASF, Lampronol Black BR from ICI (C.I. SolventBlack 35), Morton Morplas Magenta 36 (C.I. Solvent Red 172), metalphthalocyanine colorants such as those disclosed in U.S. Pat. No.6,221,137, the disclosure of which is totally incorporated herein byreference, and the like. Polymeric dyes can also be used, such as thosedisclosed in, for example, U.S. Pat. No. 5,621,022 and U.S. Pat. No.5,231,135, the disclosures of each of which are herein entirelyincorporated herein by reference, and commercially available from, forexample, Milliken & Company as Milliken Ink Yellow 869, Milliken InkBlue 92, Milliken Ink Red 357, Milliken Ink Yellow 1800, Milliken InkBlack 8915-67, uncut Reactant Orange X-38, uncut Reactant Blue X-17,Solvent Yellow 162, Acid Red 52, Solvent Blue 44, and uncut ReactantViolet X-80.

Pigments are also suitable colorants for the curable phase change inks.Examples of suitable pigments include PALIOGEN Violet 5100 (commerciallyavailable from BASF); PALIOGEN Violet 5890 (commercially available fromBASF); HELIOGEN Green L8730 (commercially available from BASF); LITHOLScarlet D3700 (commercially available from BASF); SUNFAST Blue 15:4(commercially available from Sun Chemical); Hostaperm Blue B2G-D(commercially available from Clariant); Hostaperm Blue B4G (commerciallyavailable from Clariant); Permanent Red P-F7RK; Hostaperm Violet BL(commercially available from Clariant); LITHOL Scarlet 4440(commercially available from BASF); Bon Red C (commercially availablefrom Dominion Color Company); ORACET Pink RF (commercially availablefrom Ciba); PALIOGEN Red 3871 K (commercially available from BASF);SUNFAST Blue 15:3 (commercially available from Sun Chemical); PALIOGENRed 3340 (commercially available from BASF); SUNFAST Carbazole Violet 23(commercially available from Sun Chemical); LITHOL Fast Scarlet L4300(commercially available from BASF); SUNBRITE Yellow 17 (commerciallyavailable from Sun Chemical); HELIOGEN Blue L6900, L7020 (commerciallyavailable from BASF); SUNBRITE Yellow 74 (commercially available fromSun Chemical); SPECTRA PAC C Orange 16 (commercially available from SunChemical); HELIOGEN Blue K6902, K6910 (commercially available fromBASF); SUNFAST Magenta 122 (commercially available from Sun Chemical);HELIOGEN Blue D6840, D7080 (commercially available from BASF); SudanBlue OS (commercially available from BASF); NEOPEN Blue FF4012(commercially available from BASF); PV Fast Blue B2GO1 (commerciallyavailable from Clariant); IRGALITE Blue BCA (commercially available fromCiba); PALIOGEN Blue 6470 (commercially available from BASF); SudanOrange G (commercially available from Aldrich), Sudan Orange 220(commercially available from BASF); PALIOGEN Orange 3040 (BASF);PALIOGEN Yellow 152, 1560 (commercially available from BASF); LITHOLFast Yellow 0991 K (commercially available from BASF); PALIOTOL Yellow1840 (commercially available from BASF); NOVOPERM Yellow FGL(commercially available from Clariant); Ink Jet Yellow 4G VP2532(commercially available from Clariant); Toner Yellow HG (commerciallyavailable from Clariant); Lumogen Yellow D0790 (commercially availablefrom BASF); Suco-Yellow L1250 (commercially available from BASF);Suco-Yellow D1355 (commercially available from BASF); Suco Fast YellowD1355, D1351 (commercially available from BASF); HOSTAPERM Pink E 02(commercially available from Clariant); Hansa Brilliant Yellow 5GX03(commercially available from Clariant); Permanent Yellow GRL 02(commercially available from Clariant); Permanent Rubine L6B 05(commercially available from Clariant); FANAL Pink D4830 (commerciallyavailable from BASF); CINQUASIA Magenta (commercially available from DUPONT); PALIOGEN Black L0084 (commercially available from BASF); PigmentBlack K801 (commercially available from BASF); and carbon blacks such asREGAL 330™ (commercially available from Cabot), Nipex 150 (commerciallyavailable from Degusssa) Carbon Black 5250 and Carbon Black 5750(commercially available from Columbia Chemical), and the like, as wellas mixtures thereof.

Also suitable are the colorants disclosed in U.S. Pat. Nos. 6,472,523,6,726,755, 6,476,219, 6,576,747, 6,713,614 , 6,663,703, 6,755,902,6,590,082, 6,696,552, 6,576,748, 6,646,111, 6,673,139, 6,958,406,6,821,327, 7,053,227, 7,381,831 and 7,427,323, the disclosures of eachof which are incorporated herein by reference in their entirety.

The colorant may be included in the ink composition in an amount offrom, for example, about 0.1 to about 15% by weight of the inkcomposition, such as about 2.0 to about 9% by weight of the inkcomposition.

Initiators

The curable phase change ink composition may optionally include aninitiator, such as, for example, a photoinitiator. In embodiments, suchan initiator is desirable for assisting in curing of the ink.

In embodiments, a photoinitiator that absorbs radiation, for example UVlight radiation, to initiate curing of the curable components of the inkmay be used. As the photoinitiator for ink compositions of embodimentsthat are cured by free-radical polymerization, for instance, inkcompositions containing acrylate groups or inks comprised of polyamides,mention may be made of photoinitiators such as benzophenones, benzoinethers, benzil ketals, α-hydroxyalkylphenones, α-hydroxketones,α-alkoxyketones, α-aminoketones, α-alkoxyalkylphenones,α-aminoalkylphenones and acylphosphine photoinitiators sold under thetrade designations of IRGACURE and DAROCUR from Ciba. Specific examplesof suitable photoinitiators include2,4,6-trimethylbenzoyldiphenylphosphine oxide (available as BASF LUCIRINTPO); 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide (available asBASF LUCIRIN TPO-L); bis(2,4,6-trimethylbenzoyl)-phenyl-phosphine oxide(available as Ciba IRGACURE 819) and other acyl phosphines;2-methyl-1-(4-methylthio)phenyl-2-(4-morphorlinyl)-1-propanone(available as Ciba IRGACURE 907) and1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methylpropan-1-one (availableas Ciba IRGACURE 2959); 2-benzyl 2-dimethylamino 1-(4-morpholinophenyl)butanone-1 (available as Ciba IRGACURE 369);2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)-benzyl)-phenyl)-2-methylpropan-1-one(available as Ciba IRGACURE 127);2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)-butanone(available as Ciba IRGACURE 379); titanocenes; isopropylthioxanthone;1-hydroxy-cyclohexylphenylketone; benzophenone;2,4,6-trimethylbenzophenone; 4-methylbenzophenone;diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide;2,4,6-trimethylbenzoylphenylphosphinic acid ethyl ester;oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl) propanone);2-hydroxy-2-methyl-1-phenyl-1-propanone; benzyl-dimethylketal; andmixtures thereof. Mention may also be made of amine synergists, i.e.,co-initiators that donate a hydrogen atom to a photoinitiator andthereby form a radical species that initiates polymerization (aminesynergists can also consume oxygen dissolved in the ink—as oxygeninhibits free-radical polymerization its consumption increases the speedof polymerization), for example such as ethyl-4-dimethylaminobenzoateand 2-ethylhexyl-4-dimethylaminobenzoate. This list is not exhaustive,and any known photoinitiator that initiates the free-radical reactionupon exposure to a desired wavelength of radiation such as UV light canbe used without limitation.

In embodiments, the photoinitiator may absorb radiation of about 200 toabout 420 nm wavelengths in order to initiate cure, although use ofinitiators that absorb at longer wavelengths, such as the titanocenesthat may absorb up to 560 nm, can also be used without restriction.

The total amount of initiator included in the ink composition may befrom, for example, about 0.5 to about 15% by weight, such as from about1 to about 10% by weight, of the ink composition.

Antioxidants

The curable phase change ink compositions can also optionally contain anantioxidant. The optional antioxidants of the ink compositions protectthe images from oxidation and also protect the ink components fromoxidation during the heating portion of the ink preparation process.Specific examples of suitable antioxidant stabilizers include NAUGARD™524, NAUGARD™ 635, NAUGARD™ A, NAUGARD™ 1-403, and NAUGARD™ 959,commercially available from Crompton Corporation, Middlebury, Conn.;IRGANOX™ 1010, and IRGASTAB UV 10, commercially available from CibaSpecialty Chemicals; GENORAD 16 and GENORAD 40 commercially availablefrom Rahn A G, Zurich, Switzerland, and the like.

When present, the optional antioxidant is present in the inkcompositions of embodiments in any desired or effective amount, such asat least about 0.01% by weight of the ink composition, at least about0.1% by weight of the ink composition, or at least about 1% by weight ofthe ink composition.

Ink Composition Preparation and Use

The curable phase change inks of embodiments may be prepared by anysuitable technique. As an example, the inks may be prepared by firstcombining the initiator components with the curable monomer and optionaloligomers mixture, adding the specified amount of gellant, which may beless than 50% by weight or less than 15% by weight of the inkcomposition, optionally adding the specified amount of reactive waxwhich may be less than 50% by weight or less than 10% by weight, heatingthe mixture to obtain a single phase with low viscosity and thereafteradding this hot mixture slowly to a heated pigment dispersion (which maybe a concentrate) while agitating the mixture. The ink composition maythen be filtered, optionally at an elevated temperature, through afilter to remove extraneous particles. The method of preparation for theink compositions may be modified so as to accommodate the type ofreactive gelling agents used for the preparation of the inkcompositions. For example, a concentrate of the gelling agent may beprepared in one of the components of the ink composition prior to theaddition of the other components. Solutions containing co-gelling agentscan also be prepared by a method similar to the one described above.Further examples of ink preparation methods are set forth in theExamples below.

The ink compositions may be employed in an apparatus for direct printingink-jet processes, wherein when droplets of the melted ink are ejectedin an imagewise pattern onto a recording substrate, the recordingsubstrate is a final recording substrate. The recording substrate may beat any suitable temperature during recording. In embodiments, therecording substrate may be at room temperature. However, in someembodiments, the substrate may be heated or cooled to have a surfacetemperature that is, for example, within the range of gel-phasetransition temperatures for the ink composition. For example, thesubstrate may be maintained at a temperature of about 5° C. to about160° C., such as from about 15° C. to about 50° C., or from about 20° C.to about 40° C. In this way, the jetted ink may be made to rapidly forma gel. Thus, the ink may be heated to a first temperature at which theink may be jetted, for instance, above the gel-transition temperature ofthe ink composition, which first temperature may be, for example, fromabout 50° C. to about 100° C. The second temperature at which the gelforms is less than the first temperature, for example is from about 5°C. to about 75° C., as discussed above.

The ink compositions can also be employed in indirect (offset) printingink jet applications, wherein when droplets of the melted ink areejected in an imagewise pattern onto a recording substrate, therecording substrate is an intermediate-transfer member and the ink inthe imagewise pattern is subsequently transferred from theintermediate-transfer member to a final recording substrate.

The ink compositions may be jetted onto an intermediate-transfersubstrate, for instance, an intermediate-transfuse drum or belt. In asuitable design, the image may be applied by jetting appropriatelycolored ink compositions during, for instance, four to eighteenrotations (incremental movements) of the intermediate-transfuse memberwith respect to the ink jet head, in other words, there is a smalltranslation of the printhead with respect to the substrate in betweeneach rotation. This approach simplifies the printhead design, and thesmall movements ensure good droplet registration. Transfuse, or atransfer and fusing step, is desirable in forming the image as transfuseenables a high quality image to be built up on a rapidly rotatingtransfer member. Transfuse typically involves jetting the inkcomposition from the ink-jet head onto an intermediate-transfer membersuch as a belt or drum, such as the transfuse member. This allows theimage to be rapidly built onto the transfuse member for subsequenttransfer and fusing to an image-receiving substrate. Alternatively, thesame image build-up can be carried out directly on the image substrate,for example, paper.

The intermediate-transfer member may take any suitable form, such as adrum or belt. The member surface may be at room temperature, although inembodiments the member may be heated to have a surface temperature thatis, for example, within the gel-state temperature range for the inkcomposition. For example, the surface may be maintained at a temperatureof about 25° C. to about 100° C., such as from about 30° C. to about 70°C., or from about 30° C. to about 50° C. In this way, the jetted ink maybe made to rapidly form a gel, which gel is maintained on the surface ofthe transfer member until transfer to the image-receiving substrate.Thus, the ink may be heated to a first temperature at which the ink maybe jetted, for instance, above the gel-transition temperature of the inkcomposition, which first temperature may be, for example, from about 40°C. to about 100° C. The second temperature at which the gel forms isless than the first temperature, for example is from about 25° C. toabout 100° C., as discussed above.

Once upon the intermediate-transfer member surface, the jetted inkcomposition may be exposed to radiation to a limited extent so as toaffect a limited curing of the ink upon the intermediate-transfer membersurface. This intermediate curing is not to cure the ink composition toits full extent, but merely to assist in setting the jetted ink so thatit may be transferred to the image receiving substrate with theappropriate amount of penetration, which requires the ink droplets tohave a certain rheology before transfer. For controlling the extent ofthe curing if an intermediate cure is practiced, reference is made toco-pending U.S. Patent Application Publication Nos. 2006/0158496 and2006/0119686, each incorporated herein by reference. Thisintermediate-curing step is not necessary in embodiments in which thegel state is sufficient to impart the desired rheology to the inkdroplets.

Following jetting to the intermediate-transfer member and optionalintermediate curing thereon, the ink composition is thereaftertransferred to an image receiving substrate. The substrate may be anysuitable material such as non-porous flexible food packaging substrates,adhesives for food packaging paper, foil-laminating, fabric, plastic,glass, metal, etc.

Following transfer to the substrate or jetting to the substrate ifdirect printing is employed, an image may then be contacted with arotating contact member, which may or may not comprise a release layerin the form of an oil or aqueous solution as disclosed in Xerox DocketNo. 20090780-US-NP and related applications in order to achieve levelingof the image. The ink composition is then cured by exposing the image onthe substrate to radiation. For example, radiation having an appropriatewavelength, mainly the wavelength at which the ink initiator absorbsradiation, may be used. This initiates the curing reaction of the inkcomposition. The radiation exposure need not be long, and may occur forexample, about 0.05 to about 10 seconds, such as from about 0.2 to about2 seconds. These exposure times are more often expressed as substratespeeds of the ink composition passing under a UV lamp. For example, themicrowave energized, doped mercury bulbs available from UV Fusion areplaced in an elliptical mirror assembly that is 10 cm wide; multipleunits may be placed in series. Thus, a belt speed of 0.1 ms⁻¹ wouldrequire 1 second for a point on an image to pass under a single unit,while a belt speed 4.0 ms⁻¹ would require 0.2 seconds to pass under fourbulb assemblies. The energy source used to initiate crosslinking of thecurable components of the composition can be actinic, for example,radiation having a wavelength in the ultraviolet or visible region ofthe spectrum, accelerated particles, for example, electron beamradiation, thermal, for example, heat or infrared radiation, or thelike. In embodiments, the energy is actinic radiation because suchenergy provides excellent control over the initiation and rate ofcrosslinking. Suitable sources of actinic radiation include mercurylamps, xenon lamps, carbon arc lamps, tungsten filament lamps, lasers,light emitting diodes, sunlight, electron beam emitters and the like.The curing light may be filtered or focused, if desired or necessary.The curable components of the ink composition react to form a cured orcross-linked network of appropriate hardness and robustness. Inembodiments, the curing is substantially complete to complete, at least75% of the curable components are cured (reacted and/or cross-linked).This allows the ink composition to be substantially hardened, andthereby to be much more scratch resistant, and also adequately controlsthe amount of show-through on the substrate.

When an indirect-printing process is used, the intermediate-transfermember can be of any desired or suitable configuration, such as a drumor roller, a belt or web, a flat surface or platen, or the like. Thetemperature of the intermediate-transfer member can be controlled by anydesired or suitable method, such as by situating heaters in or near theintermediate-transfer member, using air flow to cool the transfermember, or the like. Optionally, a layer of a sacrificial liquid can beapplied to the intermediate-transfer member prior to ejecting thedroplets of melted ink onto the intermediate-transfer member, wherebythe melted ink droplets are ejected onto the sacrificial liquid layer onthe intermediate-transfer member, as disclosed in, for example, U.S.Pat. No. 5,389,958. Transfer from the intermediate-transfer member tothe final recording substrate can be made by any desired or suitablemethod, such as by passing the final recording substrate through a nipformed by the intermediate-transfer member and a back member, which canbe of any desired or effective configuration, such as a drum or roller,a belt or web, a flat surface or platen, or the like. Transfer can becarried out at any desired or effective nip pressure, for example fromabout 5 pounds per square inch to about 2,000 pounds per square inch,such as from about 10 to about 200 pounds per square inch. The transfersurface may be hard or soft and compliant. Subsequent to transfer, theimage on the substrate is cured. The radiation to cure thephoto-polymerizable components of the ink composition may be provided bya variety of possible techniques, including but not limited to a xenonlamp, laser light, medium pressure mercury lamps, micro-wave excitedmercury lamps often known as a H bulb, doped mercury lamps oftenreferred to as D or V bulbs, LED etc. Without being limited to anyspecific theory, it is believed that in this embodiment, the inkcomposition is transferred to the final recording substrate in asemi-solid state, facilitating penetration of the ink composition intothe final substrate (paper fibers, for example) and enabling improvedadhesion, reduced show-through, and reduced pile height.

The following examples of curable phase change ink compositions furtherillustrate the foregoing embodiments. These Examples are illustrative ofdifferent compositions and conditions that can be utilized in practicingthe disclosure. All proportions are by weight unless otherwiseindicated. It will be apparent, however, that the disclosure can bepracticed with many types of compositions and can have many differentuses in accordance with the disclosure above and as pointed outhereinafter.

EXAMPLES

Ten different ink formulations were prepared as described below in Table1 and Table 2. Inks A-J were each prepared on a 20 gram scale bycombining all components, except the pigment dispersion, and mixingthese components at 90° C. and 200 rpm for approximately 1 hour. After 1hour, the pigment dispersion was added to each ink and combined inkcomposition was stirred at 90° C. for an additional hour. All inks werefully miscible, giving solutions with a pourable viscosity at elevatedtemperatures and forming stiff gels when cooled to room temperature.Furthermore, of Inks A-B and D-E each contain “Crystalline PolyesterResin #1”, wherein the characteristics of this crystalline polyesterresin being a M_(w) of 22,000 Da, a M_(N) of 10.2 and a polydispersityof 2.2. Additionally, Inks F-G and I-J each contain “CrystallinePolyester Resin #2”, wherein the characteristics of this crystallinepolyester resin being a M_(N) of 21,300 Da, a M_(N) of 10,200 Da and apolydispersity of 2.2. As used herein in the Examples, the crystallinepolyester resins are named using source based polymer nomenclature. Forexample, “Crystalline Polyester Resin #1” is poly(dodecanedoicacid-alt-1,9-nonanediol)ester (also referred to aspoly(nonylene-dodecanedioate) and “Crystalline Polyester Resin #2” ispoly(dodecanedoic acid-alt-(1,9-nonanediol)_(0.475)(neopentylglycol)_(0.025))ester.

TABLE 1 Components of Inks A-E Inks A B C D E Component wt % wt % wt %wt % wt % Amide Gellant 7.5% 7.5%  7.5%  7.5% 7.5% Unilin 350-  5% 5% 5% 5%  5% acrylate Irgacure 127 3.5% 3.5%  3.5%  3.5% 3.5% Irgacure 819 2% 2% 2%  2%  2% Irgacure 379  3% 3% 3%  3%  3% Irgastab UV 10 0.2%0.2%  0.2%  0.2% 0.2% Pigment  20% 20%  20%   20%  20% Crystalline 2.5%5% 0%  10%  15% Polyester Resin #1 SR 9003 56.3%  53.8%   58.8%   48.8% 43.8%  Total 100%  100%  100%  100%  100% 

TABLE 2 Components of Ink F-J Inks F G H I J Component wt % wt % wt % wt% wt % Amide Gellant 7.5% 7.5%  7.5%  7.5% 7.5% Unilin 350-  5% 5% 5% 5%  5% acrylate Irgacure 127 3.5% 3.5%  3.5%  3.5% 3.5% Irgacure 819 2% 2% 2%  2%  2% Irgacure 379  3% 3% 3%  3%  3% Irgastab UV 10 0.2%0.2%  0.2%  0.2% 0.2% Pigment  20% 20%  20%   20%  20% Crystalline 2.5%5% 0%  10%  15% Polyester Resin #2 SR 9003 56.3%  53.8%   58.8%   48.8% 43.8%  Total 100%  100%  100%  100%  100% 

Viscosity and Elastic Modulus

The temperature dependant dynamic viscosity of Example Inks A-B and F-Gwas evaluated using an RFS III controlled strain rheometer, manufacturedfrom TA Instruments equipped with a 50 mm parallel plate.

TABLE 3 Viscosity of Inks A-J Amount of Complex Viscosity (cps) Type ofCrystalline Jetting Jetting Jetting Crystalline Polyester Temp. Temp.Temp. Polyester (wt. %) Ink 90° C. 85° C. 80° C. Crystalline 2.5 A 6.107.05 8.27 Polyester 1 5 B 8.30 9.70 11.44 0 C 4.76 5.46 6.34 10 D 35.8639.47 46.21 15 E 109.56 105.35 117.15 Crystalline 2.5 F 9.48 10.76 12.46Polyester 2 5 G 9.28 10.74 12.55 0 H 6.54 7.37 8.27 10 I 39.54 42.0549.23 15 J 124.84 113.24 123.70

As shown above in Table 3, curable phase change ink compositionscontaining a crystalline polyester resin in an amount of 2.5 weightpercent (Ink A or Ink F) to 5.0 weight percent (Ink B or Ink G), of thecurable phase change ink composition have a jettable viscosity less thanabout 13 cP at a target jetting temperature range of 80° C. to 90° C.

TABLE 4 Elastic Modulus of Inks A-J Amount of Type of CrystallineCrystalline Polyester Elastic Modulus (cps) Polyester (wt. %) Ink 40° C.35° C. 30° C. Crystalline 2.5 A 1195.75 2448.47 4224.11 Polyester 1 5 B769.47 1530.25 2586.96 0 C 565.38 1224.13 2179.90 10 D 922.69 1727.618353.68 15 E 5717.99 11880.14 32666.63 Crystalline 2.5 F 964.64 1900.803258.49 Polyester 2 5 G 909.05 1760.71 2890.71 0 H 565.38 1224.132179.90 10 I 1086.98 1912.26 3114.25 15 J 1603.47 3368.89 19224.36

As shown above in Table 4, the elastic modulus increases with increasingweight % of either crystalline polyester resin. A high elastic modulusis indicative of greater cohesion which will result in less inksplitting or offset during contact leveling or transfer from anintermediate member.

Contact Leveling Analysis

Ink A and Ink F were loaded into a printhead and jetted ontotransparencies using a modified Phaser printer. The printed squares werethen fed through a contact leveling roller and followed with a chasesheet at a surface speed of 100 ips. The offset leveling surface was 25%Polyhedral oligomeric silsesquioxane (POSS) in viton.

The degree of offset to the contact leveling surface was determined bymeasuring a lightness parameter L* of the image transferred from thecontact leveling surface to the chase sheet. The lightness parameter L*was measured using a handheld X-Rite 938 spectrodensitometermanufactured by the X-Rite Corporation. A high L* value, such as greaterthan about 85 is desired, as it indicates very little offset or transferof the ink from the contact roller. However, a low L* value, such asless than about 80 is undesirable, as indicates significant offset ofthe ink to the contact leveling roller.

The L* values of the first chase sheet printed with Ink A and Ink F, andthe two comparative inks, Comparative Ink A and Comparative Ink B, areshown below in Table 4. Comparative inks A and B were prepared in exactsame manner using the exact same materials as Inks A and F, except thatComparative Ink A and Comparative Ink B did not contain any crystallinepolyester resin. Furthermore, L* values were then compared to the targetvalue (no offset) as the baseline value for paper alone, as shown belowin Table 4.

TABLE 5 L* Values Of Ink A, Ink F And Comparative Inks A-B Ink L* Ink A90.2 Ink F 89.5 Comparative Ink A 80 Comparative Ink B 84 Paper (TargetValue) 94.5

As shown above in Table 5, the L* of the chase sheet increased for Ink Aand Ink F as compared to the inks of Comparative Inks A-B indicatingless ink splitting or offset occurred for the Ink A and Ink F.

Furthermore, the difference between the L* value for the print afterleveling and the L* for the first chase sheet (ΔL*) was evaluated foreach of the above inks. This value provides an estimate of the affinityof the ink to the contact leveling roll. For example, an ink with a highaffinity to the contact leveling roll results in a decreased L* (lessdark) value for the print after leveling. These values are illustratedbelow in Table 6.

TABLE 6 L* Values Of Ink A, Ink F And Comparative Inks A-B Ink ΔL* Ink A37 Ink F 35 Comparative Ink A 20 Comparative Ink B 27.5

As shown above in Table 6, the ΔL* of the chase sheet increased for InkA and Ink F as compared to the inks of Comparative Ink A-B indicatingthat Inks A and F do not have a special affinity for the contactleveling roller.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also,various presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art, and are also intended to beencompassed by the following claims.

What is claimed is:
 1. A curable phase change ink composition, the inkcomposition comprising at least one curable acrylate or acrylatedmonomer, at least one gellant, at least one curable wax, at least one UVabsorbing photoinitiator, and at least one crystalline polyester,wherein the at least one crystalline polyester has a weight averagemolecular weight (M_(w)) of from 21,300 Dalton (Da) to 22,000 Da andwherein the at least one crystalline polyester comprises from 1-5% byweight of the ink composition.
 2. The curable phase change inkcomposition of claim 1, wherein the at least one crystalline polyesterhas a number average molecular weight (M_(n)) of from 9,000 Da to 11,000Da and a polydispersity of from 2.0 to 2.2.
 3. The curable phase changeink composition of claim 1, wherein the at least one crystallinepolyester is formed by reacting at least one organic diol with at leastone organic diacid, the organic diol being selected from the groupconsisting of ethylene glycol, propylene glycol,tetrafluoro-1,4-butanediol, diethylene glycol,2,2-dimethyl-1,3-propanediol, cyclohexanediol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, triethylene glycol, dimer diol,1,7-heptanediol, benzenedimethanol, cyclohexanedimethanol,2,2-dibutyl-1,3-propanediol, 2,8-bis(hydroxymethyl) tricycle[5.2.1.0^(2,6)]decane, 1,16-hexadecanediol and 2-phenyl-1,3-propanediol,and the organic diacid being selected from the group consisting ofadipic acid, succinic acid, sebacic acid, dodecanedioic acid, fumaricacid, isophthalic acid, terephthalic acid, oxaloacetic acid, dimerdiacid, oxalic acid, malonic acid, tetrafluorosuccinic acid, methylmalonic acid, thiodiacetic acid, diglycolic acid, maleic acid,oxaloacetic acid, acetoxyacetic acid, cyclopropane-1,1-dicarboxylicacid, glutaconic acid, itaconic acid, 1,3-acetonedicarboxylic acid,ketoglutaric acid, dimethylmalonic acid, methylsuccinic acid, glutaricacid, muconic acid, cyclobutane-1,1-dicarboxylic acid, 2-oxoadipic acid,2,2-dimethylsuccinic acid, methylglutaric acid, 3,3′-thiodipropionicacid, 4- oxoheptanedioic acid, dimethylglutaric acid,cyclohexane-1,1-dicarboxylic acid, 5-oxoazelaic acid, phenylenediaceticacid, indan-2,2-dicarboxylic acid, tetradecanedioic acid, andhexadecanedioic acid.
 4. The curable phase change ink composition ofclaim 1, wherein the crystalline polyester comprises a polyesterselected from the group consisting of poly(ethylene-adipate),poly(propylene-adipate), poly(butylene-adipate),poly(pentylene-adipate), poly(hexylene-adipate), poly(octylene-adipate),poly(ethylene-succinate), poly(propylene-succinate),poly(butylene-succinate), poly(pentylene-succinate),poly(hexylene-succinate), poly(octylene-succinate),poly(ethylene-sebacate), poly(propylene-sebacate),poly(butylene-sebacate), poly(pentylene-sebacate),poly(hexylene-sebacate), poly(octylene-sebacate),poly(nonylene-sebacate), poly(decylene-sebacate),poly(undecylene-sebacate), poly(dodecylene-sebacate),poly(ethylene-dodecanedioate), poly(propylene-dodecanedioate),poly(butylene-dodecanedioate), poly(pentylene-dodecanedioate),poly(hexylene-dodecanedioate), poly(octylene-dodecanedioate),poly(nonylene-dodecanedioate), poly(decylene-dodecandioate),poly(undecylene-dodecandioate), poly(dodecylene-dodecandioate),poly(ethylene-fumarate), poly(propylene-fumarate),poly(butylene-fumarate), poly(pentylene-fumarate),poly(hexylene-fumarate), poly(octylene-fumarate),poly(nonylene-fumarate), poly(decylene-fumarate),copoly(5-sulfoisophthaloyl)-copoly(ethylene-adipate),copoly(5-sulfoisophthaloyl)-copoly(propylene-adipate),copoly(5-sulfoisophthaloyl)-copoly(butylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate),copoly(5-sulfoisophthaloyl)-copoly(ethylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(propylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(butylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(pentylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(hexylene-succinate), copoly(5-sulfoisophthaloyl)-copoly(octylene-succinate), copoly(5-sulfo-isophthaloyl)-copoly(ethylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(butylenes-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), and combinationsthereof.
 5. The curable phase change ink composition of claim 1, whereinthe curable phase change ink composition has a jetting temperature offrom about 70° C. to about 100° C.
 6. The curable phase change inkcomposition of claim 1, wherein the curable phase change ink compositionhas a jetting temperature of from about 60° C. to about 100° C.
 7. Thecurable phase change ink composition of claim 1, wherein the curablephase change ink composition has a gelling temperature of from about 25°C. to about 70° C.
 8. The curable phase change ink composition of claim1, wherein the ink composition has an elastic modulus (G′) of from about3000 Pa to about 4000 Pa, and a viscosity of 10⁴ mPa·s to 10^(6.5) mPa·sat a gelling temperature of 25° C. to 35° C., and wherein the inkcomposition has a viscosity of from 3 to 15 mPa·s at a jettingtemperature of from 60° C. to 100° C.
 9. The curable phase change inkcomposition of claim 1, wherein the at least one crystalline polyesteris selected from the group consisting of poly(dodecanedoicacid-alt-1,9-nonanediol)ester and poly(dodecanedoicacid-alt-(1,9-nonanediol)_(0.475)(neopentyl glycol)_(0.025))ester. 10.The curable phase change ink composition of claim 1, wherein the curableacrylate or acrylated monomer is selected from the group consisting ofmultifunctional acrylate monomers, acrylated esters, acrylated ethers,acrylated epoxies, and acrylated urethanes.
 11. The curable phase changeink composition of claim 1, wherein the at least one curable acrylate oracrylated monomer comprises propoxylated neopentyl glycol diacrylate.12. An ink printing device comprising: a curable phase change inkcomposition for printing onto a substrate, an ink jetting device, acontact leveling member or roller, an optional intermediate transfermember, and a curing device which cures the jetted curable ink, whereinthe ink composition comprises at least one curable acrylate or acrylatedmonomer, at least one amide gellant, at least one curable wax, at leastone UV absorbing photoinitiator, and at least one crystalline polyester,wherein the crystalline polyester has a weight average molecular weight(M_(w)) of from 21,300 Dalton (Da) to 22,000 Da and wherein the at leastone crystalline polyester comprises from 1-5% by weight of the inkcomposition.
 13. The curable phase change ink composition of claim 12,wherein the at least one crystalline polyester has a number averagemolecular weight (M_(n)) of from 9,000 Da to 11,000 Da and apolydispersity of from 2.0 to 2.2.
 14. The ink printing device of claim12, wherein the at least one crystalline polyester is formed by reactingat least one organic diol with at least one organic diacid or organicdiester, the organic diol being selected from the group consisting ofethylene glycol, propylene glycol, tetrafluoro-1,4-butanediol,diethylene glycol, 2,2-dimethyl-1,3-propanediol, cyclohexanediol,1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, triethylene glycol,dimer diol, 1,7-heptanediol, benzenedimethanol, cyclohexanedimethanol,2,2-dibutyl-1,3-propanediol, 2,8-bis(hydroxymethyl) tricycle[5.2.1.0^(2,6)]decane, 1,16-hexadecanediol and 2-phenyl-1,3-propanediol,and the organic diacid being selected from the group consisting ofadipic acid, succinic acid, sebacic acid, dodecanedioic acid, fumaricacid, isophthalic acid, terephthalic acid, oxaloacetic acid, dimerdiacid, oxalic acid, malonic acid, tetrafluorosuccinic acid, methylmalonic acid, thiodiacetic acid, diglycolic acid, maleic acid,oxaloacetic acid, acetoxyacetic acid, cyclopropane-1,1-dicarboxylicacid, glutaconic acid, itaconic acid, 1,3-acetonedicarboxylic acid,ketoglutaric acid, dimethylmalonic acid, methylsuccinic acid, glutaricacid, muconic acid, cyclobutane-1,1-dicarboxylic acid, 2-oxoadipic acid,2,2-dimethylsuccinic acid, methylglutaric acid, 3,3′-thiodipropionicacid, 4- oxoheptanedioic acid, dimethylglutaric acid,cyclohexane-1,1-dicarboxylic acid, 5-oxoazelaic acid, phenylenediaceticacid, indan-2,2-dicarboxylic acid, tetradecanedioic acid, andhexadecanedioic acid.
 15. The ink printing device of claim 12, whereinthe crystalline polyester comprises a polyester selected from the groupconsisting of poly(ethylene-adipate), poly(propylene-adipate),poly(butylene-adipate), poly(pentylene-adipate), poly(hexylene-adipate),poly(octylene-adipate), poly(ethylene-succinate),poly(propylene-succinate), poly(butylene-succinate),poly(pentylene-succinate), poly(hexylene-succinate),poly(octylene-succinate), poly(ethylene-sebacate),poly(propylene-sebacate), poly(butylene-sebacate),poly(pentylene-sebacate), poly(hexylene-sebacate),poly(octylene-sebacate), poly(nonylene-sebacate),poly(decylene-sebacate), poly(undecylene-sebacate),poly(dodecylene-sebacate), poly(ethylene-dodecanedioate),poly(propylene-dodecanedioate), poly(butylene-dodecanedioate),poly(pentylene-dodecanedioate), poly(hexylene-dodecanedioate),poly(octylene-dodecanedioate), poly(nonylene-dodecanedioate),poly(decylene-dodecandioate), poly(undecylene-dodecandioate),poly(dodecylene-dodecandioate), poly(ethylene-fumarate),poly(propylene-fumarate), poly(butylene-fumarate),poly(pentylene-fumarate), poly(hexylene-fumarate),poly(octylene-fumarate), poly(nonylene-fumarate),poly(decylene-fumarate),copoly(5-sulfoisophthaloyl)-copoly(ethylene-adipate),copoly(5-sulfoisophthaloyl)-copoly(propylene-adipate),copoly(5-sulfoisophthaloyl)-copoly(butylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate),copoly(5-sulfoisophthaloyl)-copoly(ethylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(propylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(butylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(pentylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(hexylene-succinate),copoly(5-sulfoisophthaloyl)-copoly(octylene-succinate),copoly(5-sulfo-isophthaloyl)-copoly(ethylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(butylenes-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(octylene-sebacate),copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate),copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), and combinationsthereof.
 16. The curable phase change ink composition of claim 12,wherein the curable phase change ink composition has a jettingtemperature of from about 70° C. to about 100° C.
 17. The curable phasechange ink composition of claim 12, wherein the curable phase change inkcomposition has a jetting temperature of from about 60° C. to about 100°C.
 18. The curable phase change ink composition of claim 12, wherein thecurable phase change ink composition has a gelling temperature of fromabout 25° C. to about 70° C.
 19. A curable phase change ink composition,the ink composition comprising at least one curable monomer comprisingpropoxylated neopentyl glycol diacrylate, at least one gellant, at leastone curable wax, at least one UV absorbing photoinitiator, and at leastone crystalline polyester selected from the group consisting ofpoly(dodecanedoic acid-alt-1,9-nonanediol)ester and poly(dodecanedoicacid-alt-(1,9-nonanediol)_(0.475)(neopentyl glycol)_(0.025))ester,wherein the at least one crystalline polyester comprises from 1-5% byweight of the ink composition.
 20. The curable phase change inkcomposition of claim 19, wherein the at least one curable wax comprisespolyethylene acrylate wax.